Machines such as, for example, wheel loaders, track type tractors, and other types of heavy machinery can be used for a variety of tasks. These machines include a power source, which may be, for example, an engine, such as a diesel engine, gasoline engine, or natural gas engine that provides the power required to complete such tasks. Such power is directed to various tools, implements, pumps, fans, and/or other like parasitic loads to assist in performing these tasks. In addition, to effectively maneuver the machines during performance of such tasks, the machines include a transmission that is capable of transmitting power generated by the engine to various drivetrain components of the machines over a wide range of conditions.
For example, such machines commonly use a continuously variable transmission (“CVT”) to direct engine torque to traction devices, such as wheels or tracks, that propel the machine. A CVT is capable of providing an output torque to such components, at any speed within its operating range, by continuously changing the ratio of the transmission. During some operations, the engine and/or the CVT may also be used to assist in braking the machine. For example, during operations in which the machine is required to change travel directions at relatively high load, the engine and the CVT may be configured to provide a retarding torque to the traction devices in order to stop the machine.
However, in some situations the torque required to satisfy the cumulative demand of such machine components exceeds the maximum torque output of the engine. For example, in situations where the traction devices and one or more hydraulic implements of the machine each require large amounts of torque to perform respective tasks, the cumulative torque demand associated with these components may be greater than the maximum engine torque available for distribution. In such situations, known control systems typically distribute the available engine torque according to distribution rules stored in one or more look-up tables, or by using fixed torque priority values or ratios associated with the respective components.
For example, U.S. Pat. No. 6,385,970 to Kuras et al. discloses a system that includes an engine, a hydraulic CVT, and a control system in communication with the engine and the CVT. The control system of the '970 patent is paired with a hydro-mechanical drive system that is operable to sense engine speed and create an output speed signal. The control system is further operable to compare the engine speed signal to an underspeed value and produce an error signal. The error signal is used to produce a command signal that controls the transmission ratio to manage the parasitic loads receiving power from the engine.
While the control system of the '970 patent may employ various strategies to distribute engine torque including the use of look-up tables or fixed torque priority values associated with the parasitic loads, such strategies are inflexible and are typically disliked by operators of such machines. For example, preferences for optimal torque distribution between machine implements and the traction devices may vary from operator to operator. Thus, while a certain torque distribution between such components may be acceptable to a first operator of the machine, the same torque distribution may be unacceptable to a second operator of the machine. Systems similar to the control system disclosed in the '970 patent, however, do not allow operators to manually adjust the torque priority values associated with the respective machine components during operation. As a result, such systems do not allow for machine optimization based on the individual preferences of the operator.
The present disclosure is directed towards overcoming one or more of the problems as set forth above.